The sensor is S1 in this alarm that we found in a Radio Electronics magazine from May 1971. Several sensors can be used in series. The SCR supports equivalents from the 106 series.
The LM100 integrated circuit is quite old, still of a metallic enclosure type. The circuit shown in...
Found in an Electronic Design from the 90s, this circuit makes use of components from the time. The...
This circuit is from an Italian magazine of 1983, but it can be assembled with the most modern...